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Reason as a WOK
Transcript of Reason as a WOK
three terms, each of which occur twice
quantifiers which show the quanity being used ("and"/"some") example: All panthers are pink.
Che Guevera is a panther.
Therefore Che Guevera is pink. premises: logical assumptions
freshwater lakes have no sharks
humans are mortals a statement is not true or false, it is valid or invalid
truth: a property of statements and concerned with "the case"
validity: a property of arguments and concerned with the premise of the conclusion THE VALIDITY OF AN ARGUMENT
IS INDEPENDENT OF
THE TRUTH OR FALSITY OF THE
PREMISES IT CONTAINS Truth and Validity Activity: two true premises and a true conclusion
two false premises and a true conclusion
two false premises and a false conclusion make a syllogism an argument is valid if the conclusion follows from the premises an argument is invalid if the
conclusion does not follow from the premises so Structure of a Syllogism: All As are Bs.
Some As are Cs.
Therefore some Bs are Cs. A valid Structure: An invalid Structure: All As are Bs.
All Bs are Cs.
Therefore all Cs are As. Venn Diagrams Venn Diagrams help determine validity or invalidity of a syllogism All As are Bs.
Some As are Cs.
Therefore some Bs are Cs. All As are Bs.
All Bs are Cs.
Therefore all Cs are As. Which is invalid? Activity use venn diagrams to
state if valid or invalid No Martians have red noses.
Rudolph has a red nose.
Therefore Rudolph is not a Martian. Some astrologers are frauds.
Some frauds are not wealthy.
Therefore some astrologers are not wealthy. No alphas are betas.
No gammas are betas.
Therefore no gammas are alphas. Inductive Reasoning form of reasoning that goes from particular to general, from the observed to the unobserved
allows us to make generalizations about the world since induction goes beyond the immediate evidence of our senses, we cannot always rely on it
therefore, we tend to make hasty generalizations and jump to conclusions based on insufficient evidence Deduction: Induction: Definitions Reasoning from general to particular. Reasoning from particular to general. Examples All metals expand when heated.
A is a metal.
Therefore A expands when heated. Metal A expands when heated; metal B expands when heated; metal C expands when heated. Therefore all metals expand when heated. Value More certain, less informative than induction. More informative, less certain than deduction. Generalizations/Contradictions Since apples have nourished me in the past, they will nourish me today. Tomorrow apples could make me sick. Since my neighbors dog has been friendly in the past, I am confident he will not bite me today. Tomorrow, the dog may bite me. the hasty generalizations are made worse by confirmation bias Logical Generalizations 1. Look at numbers of instances.
2. Look at a variety of instances.
3. Look at counter-examples.
4. Demand evidence to support surprising claims.
5. Be aware of your subject area. examples: If a tourist is served by a rude French waiter, he may conclude that all French people are rude. Activity A businessman had just turned off the lights in the store when a man appeared and demanded money. The owner opened a cash register. The contents of the cash register were scooped up, and the man sped away. A member of the police force was notified prompty. 1. A man appeared after the owner had turned off his store lights.
2. The robber was a man.
3. The man did not demand money.
4. The man who opened the cash register was the owner.
5. The store owner scooped up the contents of the cash register and ran away.
6. Someone opened a cash register.
7. After the man who demanded money scooped up the contents of the cash register, he ran away.
8. While the cash register contained money, the story does not say how much.
9. The robber demanded money of the owner.
10. The story contains a series of events in which only three personas are referred to: the owner of the store, a man who demanded money, and a member of the police force. state true, false, or unknown A clear sign of hasty generalizations! Most people do not determine that on number six is true.
All the others are uncertain. Informal Reasoning POKs
Knowledge Issues Reasoning/Certainty
Lateral Thinking confirmation bias bias/belief bias loaded questions double standards generalizations vested interests How does reason help
people acquire knowledge
of a different form? How do 'informal' fallacies affect people's everyday lives? How does ignorance, laziness, pride and prejudice effect reasoning? What prevents people from changing perspective? Why does everything have doubt? How do hasty generalizations form and what confirms them? A man is lying dead in a field. Next to him there is an unopened package. There is no other creature in the field. How did he die? A man rode into town on Friday. He stayed three nights and then left on Friday. How come? The man's parachute failed to open!
Friday is the name of the man's horse!
The boxers are women! Two boxers are in a boxing match. The fight is scheduled for 12 rounds, but ends after 6 rounds, after one boxer knocks out the other boxer. Yet no man throws a punch. How is this possible? Thinking Rationally
Thinking "Outside of the Box" ad ignorantiam
post hoc ergo propter hoc
loaded question claiming something is true because it cannot be proven false generalizing from insufficient evidence confusing a correlation with a causal connection attacking/supporting the person, not idea assuming the truth of what you are supposed to be proving using double standards to excuse an individual/group using ambiguous language assuming that because two things are alike in some respects, they are alike in others too assuming only two black and white alternatives exist a biased question containing built-in assumptions Ad hominem:
against the man Circular reasoning:
vicious circle, begging the question How would you explain the well-known observation-supported by statistical evidence-that as the number of churches in American cities increases, so does the number of prostitutes? Ponder This Bad reasoning comes from:
prejudice and Law of identity: If A, then A.
A banana is a banana. Law of non-contradiction: Nothing can be both A, and not A.
Nothing can be both a banana and not-a-banana. Law of the excluded middle: Everything is either A or not A.
Everything is either a banana or not a banana. Can't a man and wife have a love-hate relationship?
Doesn't that mean that you can both love and not love someone?
What you really mean is that you love someone in certain ways or at certain times, but not in other ways or at other times!. Doubt Logic could be just a way to describe the way we think, rather than what really is.
Logic depends on language, and language separates things into clear-cut categories.
Nothing stays the same long enough to be identical to itself in the past. Deductive Reasoning How do we know the truths now will be the truths in the future?
Inductive reasoning is from the observed to the unobserved, so there is no way we can justify our belief in the experience that we in fact, did not experience. Inductive Reasoning Comparing the Reasonings and Works Cited: "Logic Me This: Hasty Generalization - Teen Skepchick." Teen Skepchick - The Future of Skepticism. Web. 02 Sept. 2011. http://teenskepchick.org/2011/06/13/logic-me-this-hasty-generalization/>. “What’s Your Excuse?.” Dr. Mark’s Heath Tips. Web. 2 September 2011. http://drmarkscorner.blogspot.com/2011_01_01_archive.html IDKWhat. "Ad Hominem - Oh Internet." Main Page - Oh Internet. Oh Internet. Web. 01 September 2011. <http://ohinternet.com/Ad_hominem>. "Critical Thinking 5 « Strange Pilgrim." Strange Pilgrim. Strange Pilgrim, 1 June 2007. Web. 02 September 2011. <http://strangepilgrims.wordpress.com/2007/06/01/critical-thinking-5/>. TOK Textbook The Ten Deadly Fallacies Post hoc ergo propter hoc:
after this, therefore on account of this Laws of Thought: Geometry: The Complete Course - Inductive and Deductive Reasoning - YouTube. Prod. TMWMedia. YouTube - Broadcast Yourself. YouTube, 29 Jan. 2008. Web. 12 Sept. 2011. <http://www.youtube.com/watch?v=DY1HzAnIb1A>. Remember the Structure: All As are Bs.
Some As are Cs.
Therefore some Bs are Cs.